// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_PROFILER_WIN32_STACK_FRAME_UNWINDER_H_
#define BASE_PROFILER_WIN32_STACK_FRAME_UNWINDER_H_

#include <windows.h>

#include <memory>

#include "base/base_export.h"
#include "base/macros.h"
#include "base/win/scoped_handle.h"

namespace base {

#if !defined(_WIN64)
// Allows code to compile for x86. Actual support for x86 will require either
// refactoring these interfaces or separate architecture-specific interfaces.
struct RUNTIME_FUNCTION {
    DWORD BeginAddress;
    DWORD EndAddress;
};
using PRUNTIME_FUNCTION = RUNTIME_FUNCTION*;
#endif // !defined(_WIN64)

// Traits class to adapt GenericScopedHandle for HMODULES.
class ModuleHandleTraits : public win::HandleTraits {
public:
    using Handle = HMODULE;

    static bool BASE_EXPORT CloseHandle(HMODULE handle);
    static bool BASE_EXPORT IsHandleValid(HMODULE handle);
    static HMODULE BASE_EXPORT NullHandle();

    BASE_EXPORT static const HMODULE kNonNullModuleForTesting;

private:
    DISALLOW_IMPLICIT_CONSTRUCTORS(ModuleHandleTraits);
};

// HMODULE is not really a handle, and has reference count semantics, so the
// standard VerifierTraits does not apply.
using ScopedModuleHandle = win::GenericScopedHandle<ModuleHandleTraits, win::DummyVerifierTraits>;

// Instances of this class are expected to be created and destroyed for each
// stack unwinding. This class is not used while the target thread is suspended,
// so may allocate from the default heap.
class BASE_EXPORT Win32StackFrameUnwinder {
public:
    // Interface for Win32 unwind-related functionality this class depends
    // on. Provides a seam for testing.
    class BASE_EXPORT UnwindFunctions {
    public:
        virtual ~UnwindFunctions();

        virtual PRUNTIME_FUNCTION LookupFunctionEntry(DWORD64 program_counter,
            PDWORD64 image_base)
            = 0;
        virtual void VirtualUnwind(DWORD64 image_base,
            DWORD64 program_counter,
            PRUNTIME_FUNCTION runtime_function,
            CONTEXT* context)
            = 0;

        // Returns the module containing |program_counter|. Can return null if the
        // module has been unloaded.
        virtual ScopedModuleHandle GetModuleForProgramCounter(
            DWORD64 program_counter)
            = 0;

    protected:
        UnwindFunctions();

    private:
        DISALLOW_COPY_AND_ASSIGN(UnwindFunctions);
    };

    Win32StackFrameUnwinder();
    ~Win32StackFrameUnwinder();

    // Attempts to unwind the frame represented by the stack and instruction
    // pointers in |context|. If successful, updates |context| and provides the
    // module associated with the frame in |module|.
    bool TryUnwind(CONTEXT* context, ScopedModuleHandle* module);

private:
    // This function is for internal and test purposes only.
    Win32StackFrameUnwinder(std::unique_ptr<UnwindFunctions> unwind_functions);
    friend class Win32StackFrameUnwinderTest;

    // State associated with each stack unwinding.
    bool at_top_frame_;
    bool unwind_info_present_for_all_frames_;

    std::unique_ptr<UnwindFunctions> unwind_functions_;

    DISALLOW_COPY_AND_ASSIGN(Win32StackFrameUnwinder);
};

} // namespace base

#endif // BASE_PROFILER_WIN32_STACK_FRAME_UNWINDER_H_
